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MILO G. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO TIIE KELLOGGSIVITOIIBOARD AND SUPPLY COMPANY, OF SAME PLACE..

IVI ULTIPLE SWITCHBOARD.

SPECIFICATION forming* part of Letters Patent No. 592,376, dated October26, 1897.

Application filed July 26,1890. Serial No. 360,087. (No model.) Patentedin England April 8, 1890, No. 5,295, andin Germany April 15,1890,No.63,413.

To a/ZZ whom it may concern:

Be it known that i, Mino G. KELLOGG, of Chicago, in the county of Cookand State of Illinois, temporarily residing at Stuttgart, in the Empireof Germany, have invented certain new and useful Improvements inMultiple Switchboards, of which the following is a full, clear, concise,and exact description, reference being had to the accompanying dra in g,forming a part of this specification.

This invention has been patented to me in Great Britain, No. 5,295,datedApril 8, 1890, and in Germany, No. 63,413, dated April 15, 1800.

My invention relates to a single-circuit telephone-exchange system andit consists in a system of answering, switching, testing, and

` clearing out such lines,which I shall describe and claim in detail.

In the accompanying drawing, illustrating my invention, A and A aresectional views of sections of two multiple switchboards to which thesaine lines connect. Two lines and their line-switches on the boards,their annunciators, their plugs with cords, their compoundanswering-switches, two operators outfits, including their telephonesand calling generators or batteries, and the connections of the lineswith their switches, annunciators, plugs, and cords, and of theoperators apparatus are shown in the drawing.

Each line-switch has a contact-spring which is normally in contact witha contact point or piece, and is separated from said point or piece whena switch-plug is inserted, and has a second contact-piece which isnormally insulated from the other parts, but is in connection with saidcontact point or piece when a plug is inserted. Said parts are sorelated to each other and to the switch-holes and the switch-plugs areso constructed that when a plug is inserted into a switch it separatesthe contact-spring from the Contact point or piece, connects the sprin gwith the conductor of the cord belonging to the plug, and connects saidcontact point or piece with said second or nor- 1nallyinsulatedcontact-piece.

g g are the contact-springs, While h h are contact-points on which thesprings normally bear, h' h extension-pieces to the points placed alongthe switch-holes, and j j are contact-pieces placed along theswitch-holes in front of the extension-pieces 7L' 7L and ex tending tothe front of the holes.

The holes marked Z Z are square `or rectilinear holes adapted to receivethe switch-plugs and cause them to operate the switches as described. ab are ebonite pieces on which the switch paris are mounted and throughthe fronts of which are the holes Z l.

- D D are the switclrplugs, one for each line and connected to the linethrough the conductor of its switch-cord. S S are two contactpieces forthe plugs, one, S, connected to the cord conductor and adapted to formconnection with the switch-spring, and the other, S', adapted to bridgeor connect pieces j and h of the switch when a plug is inserted.

B B are compound answering-switches,one for each line. These switchesare operated on in part by the switch-plugs of their lines and in partby the operators, as will be described. In these compoundansweringswitches l, 2, 3, 4, 5, and G are contacts, of which 2, 3, and5 are springs, and l, et, and 6 may be points and rigid. fm is a pieceadapted to support the parts,'and lo furnishes a socket or support forthe plug which belongs to the line of the switch.

n is an angle or bell-crank piece suitably pivoted, and with a knob(marked o) at one end within easy manipulation of the operator, and aprojection (marked p) at the other end adapted to engage with andoperate on the irregularly-shaped ebonite piece r, fas# tened to spring3, as shown. When the plug is in the socket of its answering-switch,(the piecenbeing in its normalposition,as shoWn,) spring 5 is forced bythe plug out of contact with 6 and spring 3 is forced into contact with2. When the plug is removed, spring 5 passes into contact with 6 andspring 3 passes from point 2 into contact with 4f. When,then, (the plugbeing removed,) the operator presses the knob o to its extreme otherposition, (in the direction shown by the arrow,) the projection p,operating on spring 3, forces it into contact with point 1, and whenthereupon the operator 'vzo releases the. knob the pressure of theVspring carries it away from point 1, and it is held by the projection pin contact with spring 2.

W and X are calling-annunciators, one for each line shown. Theseannunciators are located at the boards where their line-plugs and cordsand compound answering-switches are located.` These annunciators are awellknownA form of annunciators used in telephone exchanges. Each hastwo contacts normally separate, but brought into contact by theannunciator-drop on the drop falling and indicating a call. One of thecontactpieces u is asprin g operated upon bythe drop on falling andpressed by it int-o contact with the other contact', which is a pointand marked v.

t t are operators telephones.

S S are calling generators or batteries, and

S S are test-batteries, one of each being located at each board. G ineach case represents a ground connection. The connections are asfollows: The line'passes normally in succession through the spring g andpoint h of each of the lineswitches on the several boards, passing ineach case to the spring first. It is then connected to contact-piece Sof its switch-plug and to Acontact spring 3 of its answering.- switch.Spring 2 of the answering-switch is connected through the magnet oftheline-annunciator t0 earth. Point l of the answering-switch isconnected through the calling generator or battery to earth, while point4 is connected through the operators telephone and test-battery toearth, and spring 5 is connected to earth. All the contact-pieces jj ofthe switches of a line are connected together and to point 6 of itsanswering-switch and to one of the contacts, say n, of itslineannunciator. The other contact u of -the annunciator is connected toearth.

The operation of the system is as follows:

A subscriber, wishing a connection, operates his line-annunciator. Theoperator, observing the indication, withdraws the line-plug from itsnormal position in its answeringswitch and by so doing disconnects theline from its ground connection through the annunciator and connects theline to the ground through his telephone and test-battery. This is doneby the opening of contacts 2 and 3 and the closing of contacts Sand 4.At the same time all the contact-pieces jj of the switches of the lineare connected to earth through the closing of the contacts 5 and 6. Theoperator then by conversation finds out what line is Wanted. He thentests the line wanted,

as will hereinafter be described,and if he finds it does not test busyhe places the plug in the switch of the line tested and moves the angleor bell-crank piece of the answeringswitch to its extreme position inthe direction indicated by the arrow and releases it. When the operatorputs theplug in the switch, the line is disconnected from its normalground 1indicated on the annunciator.

connection through its annunciator and the two lines are connectedtogether. When the angle or bell-crank piece is in its eXtreme positionin the direction of the arrow, as indicated, the calling generator orbattery,.

grounded on one side, is connected on its other side to the circuit ofthe two lines and will send a current to both lines which will ring thebell of the line wanted and will ring the bell of thecalling-subscriber, if he has in the meantime replaced his telephone onits switch. When the knob is released, the angle or bell-crank piecetakes a position, so that thecircuit ofthe two lines is grounded at thecentral oflice through the annunciator of the calling-subscriber, andany disconnecting-signal sent by either subscriber will be Theannunciators should preferably-be of high resistance and of suchconstruction as to offer considerable retardation to telephone-currents.

When the operator desires to listen to the i circuit of the two lines todetermine whether they are through conversation, he merely replaces themovable piece of the answeringswitch toits normal position and histelephone grounded at one end is connected on its other side to theircircuit.

The test system is as follows: Vhen a lineannunciator vindicates a callor the line is brought into use either by the withdrawal of itsswitch-plug from its normal position or by the introduction of a pluginto one of its switches, the contact-piecesj j of the switches of theline are connected to the ground. the first case the connection is madeby the closing of the contact-points of the annunciator, in the secondcase by the closing of the contacts 5 and 6 caused by the withdrawal ofthe plug, and the third case by the connection established between h andj of the switch used through the medium of the piece s of the plug. Whenthe line-annunciator does not indicate a call and the line is notswitched, the contact-piecesj j of the line are open to the ground.. Theoperator on testing IOO a line places the tip of the switch-plug of theV calling-line on the contact piece j of the switch of the tested line,and thereby through the answering-switch and the contact made connectshis telephone and test battery grounded on the other side to thecontactl scribers line is reserved to his own use from the very momentwhen he operates his calling generator or battery and the service of theexchange will be more satisfactory to him and the operators. Thisfeature of my invention is applicable to other systems of operations andof lines in ways which will now be apparent to those skilled in the art.

The operations of makingaconnection are, first, to remove the line-plugfrom its answering-switch; second, to test with the same plug the linewanted; third, to insert the plug in the switch of the line wanted;fourth, to move the angle or bell-crank piece of the answering-switch toits limit of motion, as indicated.

To disconnect two lines, the operator merely removes the plug from theswitch and places it in its normal position and places the angle orbell-crank piece in its normal position, as shown.

I claim as my invention and desire to secure by Letters Patentl. In atelephone-exchange system, a telephone-line and a switch-plug connectedto the line by a flexible conductiiigcoid, in combination with anoperators telephone, the lineannunciator, a compound answering-switchfor the line into which the plug is normally placed, a contact-point insaid switch conneeted with the line, a second point connected with theground through the ann unciator, and a third point connected to the ground through Jthe telephone, said first and second points being closedwhile the plug isiu the switch but automatically opened on thewithdrawal of the plug, and said first and third mentioned points beingopen while the plug is in the switch but automatically closed 011 thewithdrawal of the plug, and a commutator-piece Vin said switch adaptedto be moved by the operator to close said first and second mentionedpoints, and open said first and third mentioned points, substantially asset forth.

2. In a telephoneexchange system, a telephone-line and a switclrplugconnected to the line by a iieXible conducting-cord, in combination withan operators telephone, a compound answering-switch into which the plugis normally placed, a pair of contacts in said switch closed to eachother while the plug is in the switch, but automatically opened on thewithdrawal of the plug, to one of which the line is connected and to theother of which the ground is connected, a pair of contacts open whilethe plug is in the switch but automatically closed on the withdrawal ofthe plug, to one of which the line is connected and the other of whichis grounded through the telephone, and a commutator-piece adapted, whenthe plug is out of the switch, to be moved by the operator to close saidiirst pair and open said second pair of contacts, substantially as setforth.

3. In a telephone-exchange system, a telephone-line and a switch-plu gconnected to the line by a flexible conducting-cord, in combination withan operators telephone, the lineannunciator, a compound answering-switchinto which the plug is normally placed, a pair of contacts in saidswitch closed to each other while the plug is in the switch, butautomatically opened on the withdrawal of the plug,

to one of which the line is connected and to` the telephone, and acommutatonpiece adapted, when the plug is out of the switch, to be movedby the operator to close said iirst pair and open said second pair ofcontacts, sul)- stantially as set forth.

4i. In a telephone exchange system, two lines temporarily connectedtogether in a circuit for conversation, in combination with an operatorstelephone, an lannunciator and a callin g-generator, each grounded onone side, a switching device having three contactsv to which saidtelephone, annunciator and generator are respectively connected on theirother side, a connection with the circuit of said lines, and acommutator-piece adapted at the will of the operator to close saidconnection with either of said contacts, substantially as set forth.

5. In a telephoneexchange system, two lines normally grounded throughtheir lincannunciators, and temporarily disconnected from theirannunciators and connected together in a circuit for conversation, incombination with an operators telephone, a switching device having twocontacts, one of which is grounded through the telephone, and the otherof which is grounded through one of IOO said line-annunciators, aconnection with the circuit of said lines, and a commutator-pieceadapted at the will of the operator to close said connection to eitherof said contacts, substantially as set forth.

6. In a telephone exchange system, two lines temporarily connectedtogether in a circuitfor conversation, in combination with an operatorstelephone, an annunciator and a calling-generator, each grounded on oneside, a switching device having three contacts to which said telephone,annunciator and generator are respectively connected on their otherside, a connection with the circuit of said lines, and acommutator-piece adapted at the will of the operator to be placed inthree positions, in the first of which said connection is groundedthrough the telephone, in the second of which it is grounded through theannunciator, and in the third of which it is grounded through thegenerator, substantially as set forth.

7. In a telephone-exchange system, a telephone-line and a switch-plugconnected to the line by a fiexible conducting-cord, in combination withatest-circuit for the line normally open, a switching device into whichthe plug is normally placed, a pair of contacts in said switchingdevice, normally open, but closed on the withdrawal of the plug, to oneof which the test-wire is connected and to the other of which the groundis connected, an an- IIO nunciator for the line and a pair of contactsin the annunciator, normally open but closed While the annunciatorindicates a call, to one of several boards, a switehplug for the lineconnected to the line with a flexible conductor and adapted to be placedin the switches of other lines, and a line-annunciator normally in thecircuit of the line, in combination with a switching device for the pluginto Which the plug is normally placed, a normally open test-circuit forthe line, a pair of contacts in each of said switches, normally ,openbut closed While a switch-plug is inserted into the switch, a pair ofcontacts in said sWitch ing device, normally open butclosed While theplug is Withdrawn from the device, and a pair of contacts in saidannunciator,normally open but closed While the annunciator indicates acall, one contact of each pair being connected With the ground and theother With Said normally open test-Wire, substantially as set forth.

9. In a telephone-exchange system, a teleconnected to the line by aflexible conductor and adapted to be placed in the switches of otherlines, and a line-annunciator, normally in the circuit of the line incombination with a switching device for the plug into Which the plugis'normally placed, a normally open testcircuit for the line, a pair ofcontacts in each of said switches, normally open but closed While aswitch-plug is inserted into the switch, a pair of contacts in saidswitching device, normally open but closed While the plug is Withdrawnfrom the device, a pair of contacts in said annunciator, normally openbut closed While the annunciator indicates a call, one contact of eachpair being connected With the ground, and c the other With said normallyopen test-Wire, test receiving instruments, one at each board, eachgrounded on one side and connected on the other side to a plug or deviceadapted to be brought into connection with said normally open testwvire,and a battery between the ground and each test-plug,

I MILO G. KELLOGG.

Witnesses:

EMIL ABENHEIM,

C. STRICH-CHAPELL.

